1. Field of the Invention
The present invention relates generally to a sheet-fed printing press, or more precisely, to a power feeder apparatus for a rotary shaft such as a plate cylinder shaft of the printing press.
2. Description of the Prior Art
In order to correct the position of a printing plate and thus to effect register adjustment by electric driving means such as a motor incorporated in a plate cylinder, it is necessary to supply power at will from a still machine side to a plate cylinder shaft which is rotating at high speed. The term "power" used herein includes a relatively large current for driving the motor as well as a relatively small control current for controlling a potentiometer fitted to the motor.
In German patent laid-open DE 4140013 by the same applicant as in the present application, a power feeder apparatus for a rotary shaft is disclosed which comprises, as shown in FIG. 5, a rotary cylinder 104 with many slip rings 100 formed on the outer periphery thereof for electrically connecting with the rotary shaft 102; a fixed casing 106 so disposed as to surround the rotary cylinder 104; and a large number of canti-lever brushes 108 extruded from the fixed casing 106 for controllably bringing into contact with the slip rings 100.
However, such brush ring type apparatus is high in cost, because forming the slip rings on the periphery of the rotary cylinder is difficult. The rotary cylinder is somewhat long enough in the axial direction of the rotary shaft and occupies a large space. In addition, there arise sometimes errors in signal transmission due to the weak spring force of the cantilever brushes.